Officials from Iowa and Nebraska say a dangerous substance has reappeared this spring in Carter Lake. Kevin Baskins is with the Iowa Department of Natural Resources says both states have issued health alerts over the problem. He says microcystin has been detected in the lake. He says it’s a toxic substance produced by blue-green algae. Baskins says they have the ability to find the substance, but don’t know why it shows up. Baskins says the alert tells people to keep away from any skin contact with the substance. He says, “This is one that you want to avoid contact with. It’s not necessarily all over the lake, but it’s hard to predict where it’s at.” He says when you see matted algae on top of the water, that’s an indicator that the toxic algae might be present. Baskins says state health officials warn that serious illness in humans from blue-green algae is rare, but large exposure could cause skin rashes and itchy skin. And he says swallowing the contaminated water can lead to nausea, vomiting and diarrhea. Baskins says Carter Lake is popular in both states. He says the lake is on the west side of the Missouri River and is surrounded by Omaha, except for Carter Lake, which is on the shore and is considered to be Iowa. Baskins says Iowa and Nebraska officials are working together to try and find out more about the problem. He says they would like to monitor the lake more to find out why the algae becomes a problem. He says Nebraska found the algae problem in some other lakes, but this is the only lake in Iowa with the problem. Baskins says the health alert is in effect until the water samples indicate the water is safe.